Schott Ag

Michael Ziegler

Franz Ott

Rainer Erwin Eichholz

Erhard Zemsch

Thomas Maenner

Gerd Rosner

The method produces glass tubes having a predetermined inner profile according to a Vello-method or Down-Draw method, wherein molten glass emerges from an outlet orifice of a melt feed and is drawn over a shaping body to form a hollow drawing bulb, and the drawing bulb is drawn over a profile forming body downstream of the shaping body to form the predetermined inner profile. To enable a reliable, risk-free positioning of the profile forming body within the drawing bulb, the profile forming body is axially moved either from below the shaping body via an inner space of the glass tube or via an inner bore of a shaft supporting the shaping body until reaching an operational position in the inner space of the glass tube. An apparatus for performing the method is also described.

Method and apparatus for manufacturing glass tubes having a predetermined inner profile, preferably for continuously manufacturing such glass tubes

In the method molten glass emerges from an outlet opening of a melt feed. The molten glass is drawn over a shaping body so as to form a hollow drawing bulb. According to the invention, the drawing bulb is drawn over a profile forming body positioned downstream of the shaping body so that inner circumferential surfaces of the drawing bulb are deformed while abutting against outer surfaces of the profile forming body to form the predetermined inner profile. The distance between the shaping body and the profile forming body can be changed to vary the wall thickness of the glass tube.

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Mitterteich, Germany

Michael Ziegler